X-ray tube housing

ABSTRACT

A housing for an x-ray tube is described in which a tubular liner of higher tensile strength metal, such as steel, is provided on the inner surface of a housing member in order to prevent destruction of the housing member in the event a rotating anode in such tube breaks at high rotation speed. The liner can be a split sleeve of perforated sheet metal which is held in contact with the housing member by pressing a tubular shield of x-ray absorbing material, such as lead, outward to deform the shield until the liner is clamped between such shield and the inner surface of the housing.

United States Patent [191 Loughlin I Jan. 7, 1975 Inventor:

Assignee:

Filed:

Appl. No:

X-RAY TUBE HOUSING Peter A. Loughlin, Buffalo Grove, Ill.

US. Cl. 250/520, 250/523 Int. Cl. H0lj 35/16 Field of Search 250/493, 503, 505, 520,

References Cited UNITED STATES PATENTS 8/l932 Wappler 250/523 5/l964 Fengler 250/520 Primary Examiner-William F. Lindquist Attorney, Agent, or FirmStephen W. Blore [5 7] ABSTRACT A housing for an x-ray tube is described in which a tubular liner of higher tensile strength metal, such as steel, is provided on the inner surface of a housing member in order to prevent destruction of the housing member in the event a rotating anode in such tube breaks at high rotation speed. The liner can be a split sleeve of perforated sheet metal which is held in contact with the housing member by pressing a tubular shield of x-ray absorbing material, such as lead, outward to deform the shield until the liner is clamped between such shield and the inner surface of the housmg.

9 Claims, 4 Drawing Figures xuzAv TIJBE HOUSING BLACKGROU ND OF THE INVENTION The subjectmatterofthe present invention relates generally to x-ray 'tube'housings and in particular to a housing apparatus containing a tubular liner of metal of a higher tensile strength than the material of the housing member and the x-ray absorbing shield which may be provided as an inner layer over such liner.

The present housing apparatus is especially useful for containing rotating anode x-ray tubes since it prevents destruction of the housing member in'the event that the rotating anode breaks at high rotation speed so pieces fly off and shatter the x-ray tube. Previousx-ray tube housings made of aluminum or other lightweighLlow.

tensile-strength material and not employing the liner member of the present invention, have broken when the x-raytube contained in such housings shatters have electrical cable connectors 18 and 20, respectively, provided therein for supplying high voltage and current to an x-ray tube 22 supported within the intermediate housing portion 12. The x-ray tube 22 may have a rotating anode 24 and a fixed filament cathode 26 provided within an evacuated glass envelope 28 so that electrons 30 emitted by such filament strike a tarwhich-can'cause injury to patients and operating personnel. This is especially hazardous for rotating anode x-ray tubessinc'e, when the anode breaks, it is thrown outward against the'housing with great force due t centrifugalforce. I

It is, therefore, oneobject of the present invention to provide an improved x-raytube housing of substantially unbreakable construction which is lightweight and of relatively low cost to manufacture. v

' Another object of the invention is to provide such a housing which employs a tubular liner of metal of higher tensile strength than the material of the outer housing member and the x+ray absorbingshield contained therein sothat such housing member will not be destroyed in the event the x-ray tube breaks.

A further object of the invention is to provide such a housing in which the liner member is in the form of a split sleeve which is held in contact with the inner surface of the housing member by a tubular shield.

Still another object of the invention-is to providean x-ray tube housing for a rotating anode x-ray tube which is not broken when the rotating anode target mg. M

BRIEF DESCRIPTION OF THE DRAWING Other objects and advantages of the present inven 3-3 of FIG. 2 showing the x-ray tube in phantom lines;

FIG. 4 is an oblique section view of one embodiment of the liner member employed in the housing of FIGS. 1 to 3.

DESCRIPTION OF PREFERRED EMBODIMENT shatters and pieces fly off against the inside of the housget portion 31 of the anode and cause x-rays 32 to be emitted therefrom. The target anode 24 is rotated in a conventional manner by a rotor and bearing member 34 provided within the envelope 28 in response to an electromagnetic field produced by field windings (not shown) on the exterior of the envelope. The intermediate portion 12 of the housing includes an x-ray transparent window 36 of polycarbonate resin sold under the trademark Lexan or other high impact plastic material provided over an opening in a cylindrical housing member 38 of cast aluminum or other'lightweight material. The window 36 is in alignment with the focal spot on the target 31 of anode 24 from which the x-rays 32 are emitted so that such x-rays pass through such window to the exterior of the housing.

As shown in FIGSJ3 and 4, a tubular shield 40 of lead or other x-ray absorbing material is provided within the housing member 38 and covers the inner surface of such housing member except for an opening in alignment with the window 36 to prevent x-rays from being transmitted through-the housing member 38 in any areas other than such window. The lead shield 40'may be formed by several layers of lead each on the-order of about one-sixteenth inch-thick to provide a laminated shield of desiredthickness for absorbing x-rays of H maximum intensity depending'upon the voltage and current of the x-ray tube.

'A tubular liner member-42 of steeljor other high ten- .-sile strength metal is provided within thehousing mem- .ber- 38 between the shield and the inner surface of fthe housing member to provide. such housing with greater. impact strengthfilhe metal of the liner member ,42-hasa higher tensile strength than the material of the i housing member, 38 or the shield 40, For example, the

' tensile strength of -a low carbon steel liner 42 is about 80,000 lbs. per square inch, while an aluminum housing I housing member38. The tubular leadshi'eld 40 is then inserted inside the. liner 42 and'pressed'outwardly by a As shown in FIGS. 1 and 2, an x-ray tube housing 10 made in accordance with the present invention includes an intermediate housing portion12 attached between a pair of end portions 14 and 16 by releasable fluid tight seals to contain an insulating fluid l7 (liquid or gas) within the housing while enabling replacement of the x-ray tube therein. The end portions 14 and 16 member 38is-ab out 31,000 lbs. per square inchand a lead; shield inchi As shown in into thedesiredshape. and inserted into the cylindrical roller, pneumatic bag, or other means .to deform the lead shield outwardly. and thereby urge the liner 42 into intimate contact with theinner surface of the housing member 38. As a result,-the liner 42 is clamped in place between the shield and the housing member. The liner member 42 may be provided with a plurality of small holes about 0.3125 inch in diameter. having sevensixteenths inch spaced centers,.t o reduce the weight of I the liner without greatly effecting its strength. It should be noted that a larger opening 4 8is provided in the liner 42 and positioned in alignment with, the window 36 to enable the x-rays tobe transmittedthrough such liner without attenuation.

Any suitable high tensile strength'metal can be'employed for the liner 42 including nickel, titanium,- momember 40 is about6,800 lbs. per square v I FIG. 4, the liner member 42may be a split sleeve of sheet metal having a longitudinal gap 44 between theends of such sleeve.v The sleeve is rolled 3 lybdenum, stainless steel and other alloys, including low carbon steels. Suitable low carbon steels typically have a chemical composition by weight of 0.05 to 0.10 percent carbon, 0.25 to 0.50 percent manganese, 0.04 percent maximum phosphorous, 0.5 percent maximum sulphur and the balance iron. In one embodiment, the lead shield 40 and the aluminum housing 38 had wall thicknesses of 0.125 inch while the steel liner 42 was about one-fourth that thickness or about 0.03125 inch.

It is possible to make the liner 42 out of a unperforated cylinder of steel rather than the split sleeve shown in FIG. 4, but this would require the outer diameter of the shield to exactly match the inner diameter of the housing member 38. The advantage of the split sleeve embodiment of the liner 42 is that its diameter can be changed to automatically compensate for manufacturing tolerances in the inner diameter of the housing member 38. Also, while the liner 42 is shown only provided on the inner surface of the intermediate portion 12 of the housing surrounding the x-ray tube anode, it is also possible to extend the liner and the lead shield into the end portions 14 and 16 so that they extend throughout the entire length of the housing for maximum safety.

It will be obvious to those having ordinary skill in the art that many changes may be made in the abovedescribed preferred embodiment of the present invention without departing from the spirit of the invention. Therefore, the scope of the invention should only be determined by the following claims.

I claim:

1. A rotary anode x-ray tube housing apparatus comprising:

a hollow housing member having an x-ray transparent window portion;

means for mounting an x-ray tube having a rotary anode within said housing member so that x-rays emitted from said tube are transmitted through said window portion;

a tubular shield of x-ray absorbing material provided inside the housing member over the inner surface of said housing member. said shield having an opening aligned with said window portion; and tubular liner member of metal different from, and of a higher tensile strength than, the material of said housing member and said shield, said liner member being an integral, one-piece member provided within said housing member in position substantially completely surrounding said x-ray tube except for an opening aligned with said window portion to prevent destruction of the housing member in the event the x-ray tube breaks.

2. A housing apparatus in accordance with claim 1 in which the liner member is provided on the inner surface of the housing member beneath the shield and is of less thickness than the wall of the housing and the shield.

3. A housing apparatus in accordance with claim 2 in which the liner member is made of perforated sheet metal.

4. A housing apparatus in accordance with claim 1 in which the liner member is made of steel.

5. A housing apparatus in accordance with claim 4 in which the shield is made of lead.

6. A housing apparatus in accordance with claim 5 in which the housing member is made of aluminum.

7. A housing apparatus in accordance with claim 6 in which the window portion is made of a plastic material.

8. A housing apparatus in accordance with claim 1 in which the liner member is a split sleeve.

9. A housing apparatus in accordance with claim 8 in which the shield is a layer of lead which holds the split sleeve liner member in contact with the inner surface of the housing member. 

1. A rotary anode x-ray tube housing apparatus comprising: a hollow housing member having an x-ray transparent window portion; means for mounting an x-ray tube having a rotary anode within said housing member so that x-rays emitted from said tube are transmitted through said window portion; a tubular shield of x-ray absorbing material provided inside the housing member over the inner surface of said housing member, said shield having an opening aligned with said window portion; and a tubular liner member of metal different from, and of a higher tensile strength than, the material of said housing member and said shield, said liner member being an integral, one-piece member provided within said housing member in position substantially completely surrounding said x-ray tube except for an opening aligned with said window portion to prevent destruction of the housing member in the event the x-ray tube breaks.
 2. A housing apparatus in accordance with claim 1 in which the liner member is provided on the inner surface of the housing member beneath the shield and is of less thickness than the wall of the housing and the shield.
 3. A housing apparatus in accordance with claim 2 in which the liner member is made of perforated sheet metal.
 4. A housing apparatus in accordance with claim 1 in which the liner member is made of steel.
 5. A housing apparatus in accordance with claim 4 in which the shield is made of lead.
 6. A housing apparatus in accordance with claim 5 in which the housing member is made of aluminum.
 7. A housing apparatus in accordance with claim 6 in which the window portion is made of a plastic material.
 8. A housing apparatus in accordance with claim 1 in which the liner member is a split sleeve.
 9. A housing apparatus in accordance with claim 8 in which the shield is a layer of lead which holds the split sleeve liner member in contact with the inner surface of the housing member. 